when an electron jumps from the fourth orbit to the second orbit, one gets the

Options

A. second line of Paschen series
B. Second line of Balmer series
C. first line of Pfund series
D. second line of Lyman series

Answer

To solve the question of what happens when an electron jumps from the fourth orbit to the second orbit, we can follow these steps:

### Step 1: Understand the Electron Transition
When an electron transitions between energy levels (or orbits) in an atom, it either absorbs or emits energy in the form of a photon. The energy difference between these levels corresponds to the energy of the emitted or absorbed photon.

### Step 2: Identify the Initial and Final Orbits
In this case, the electron is moving from the fourth orbit (n=4) to the second orbit (n=2).

### Step 3: Determine the Series of Emission
The transitions of electrons in hydrogen-like atoms can be categorized into series based on the final energy level:
- **Lyman series**: Transitions to n=1
- **Balmer series**: Transitions to n=2
- **Paschen series**: Transitions to n=3
- **Brackett series**: Transitions to n=4
- **Pfund series**: Transitions to n=5

Since the electron is transitioning to n=2, we are interested in the Balmer series.

### Step 4: Identify the Specific Line in the Series
In the Balmer series, the lines are numbered based on the initial energy level:
- The first line corresponds to the transition from n=3 to n=2.
- The second line corresponds to the transition from n=4 to n=2.

Since our transition is from n=4 to n=2, it corresponds to the second line of the Balmer series.

### Conclusion
When an electron jumps from the fourth orbit to the second orbit, it emits a photon corresponding to the **second line of the Balmer series**.